Is that plumbed into the bike or do you stop and pour
Stop and pour. However, I'm moving away from using it on Iron Butt rides since it doesn't really help unless I need to stretch the distance between stops because of being in a really rural area.
Went to a car tire and it seems mileage is all over the place, but I've also seen the bike's range shortened because it (or the fuel), doesn't like cold/cooler temperatures.
So figure I get 235 miles on the bike's tank. I stop, take 20 minutes to refuel, take care of paperwork, eat something quick, bathroom, etc. I ride out again and repeat...so 470 miles, 40 minutes down time.
Now let's use the RotoPax. I ride 235 miles and stop to dump gas from it. That takes 10 minutes (about half is the actual pouring and the rest is removing the straps, etc. Despite how much range I can get out of those 3 gallons, I have to stop at 350, so only about 115 miles max (and frequently less). Now I am making a second stop to refill both the tank and the RotoPax, have about 30 minutes of downtime, and have gone only 350 miles (versus the 470 mentioned earlier).
An auxiliary tank plumbed into the bike makes more sense (technically can ride 350 miles, refuel, ride another 350 miles), but I really hate how they look and I have no real desire to do all of that work running the lines.